Artificial grammar learning in pigeons

In two experiments, we developed a new methodology for studying complex stimulus control by spatial sequences of letters generated by artificial grammars. An artificial grammar is a system of rules that defines which letter sequences or strings are “grammatical.” In Experiment 1, pigeons learned to respond differently to strings conforming to a grammar versus strings that were nongrammatical distortions. Several different criteria all suggested that performance was controlled both by some short chunks of strings shared between reinforced training strings and novel transfer strings and by more complex sequential regularities. In Experiment 2, pigeons quickly and accurately learned to respond differently to strings conforming to one or the other of two different artificial grammars. As in Experiment 1, performance was controlled both by some short chunks and by more complex sequential regularities. The results are interpreted in terms of family resemblance and pose new goals for theories of complex stimulus control.     

An investigation of ambiguous-cue learning in pigeons

Two experiments demonstrated that pigeons can solve a simultaneous discrimination in which on half the trials the positive and an ambiguous cue (A) are presented and on half the trials choice is between A and the negative stimulus. In Experiment 1, where a relatively nondistinctive A cue was used, performance on the former type of trial was superior to that shown on the latter. In Experiment 2, where a distinctive A cue was provided, this pattern of results was reversed. These findings are interpreted in terms of an approach-avoidance explanation first proposed by Leary (1958). Experiment 3 tested and confirmed a central prediction of this explanation by showing that in an orthodox simultaneous discrimination, occasional reinforcements of the negative stimulus produce less accurate performance than do nonreinforcements of the positive.     

The nature of discrimination learning in pigeons

The results from five experiments are considered in relation to two of Spence's (1937, 1938) proposals concerning discrimination learning. In Experiments 1 and 2, we investigated whether his ideas about the interaction between excitatory and inhibitory generalization gradients can be used to understand how animals solve a complex patterning discrimination. The results supported a development of his proposals as put forward by Pearce (1994), provided a modification was made to Pearce's rulefor determining the shape ofthe generalization gradient. In Experiments 3, 4, and 5, we examined whether animals would pay more attention to stimuli that are relevant, rather than irrelevant, to the solution of a discrimination. The results supported this proposal for stimuli comprising visual patterns, but not for those comprising plain colors. The results also indicated that change of attention was a consequence of preliminary receptor-exposure acts, as envisaged by Spence, and not of more central changes in attention.     

The neuroscience of perceptual categorization in pigeons: A mechanistic hypothesis

We are surrounded by an endless variation of objects. The ability to categorize these objects represents a core cognitive competence of humans and possibly all vertebrates. Research on category learning in nonhuman animals started with the seminal studies of Richard Herrnstein on the category “human” in pigeons. Since then, we have learned that pigeons are able to categorize a large number of stimulus sets, ranging from Cubist paintings to English orthography. Strangely, this prolific field has largely neglected to also study the avian neurobiology of categorization. Here, we present a hypothesis that combines experimental results and theories from categorization research in pigeons with neurobiological insights on visual processing and dopamine-mediated learning in primates. We conclude that in both fields, similar conclusions on the mechanisms of perceptual categorization have been drawn, despite very little cross-reference or communication between these two areas to date. We hypothesize that perceptual categorization is a two-component process in which stimulus features are first rapidly extracted in a feed-forward process, thereby enabling a fast subdivision along multiple category borders. In primates this seems to happen in the inferotemporal cortex, while pigeons may primarily use a cluster of associative visual forebrain areas. The second process rests on dopaminergic error-prediction learning that enables prefrontal areas to connect top down the relevant visual category dimension to the appropriate action dimension.     

Testing the double-deficit hypothesis in an adult sample

The double-deficit hypothesis of dyslexia posits that reading deficits are more severe in individuals with weaknesses in phonological awareness and rapid naming than in individuals with deficits in only one of these reading composite skills. In this study, the hypothesis was tested in an adult sample as a model of reading achievement. Participants were parents of children referred for evaluation of reading difficulties. Approximately half of all participants reported difficulty learning to read in childhood and a small subset demonstrated ongoing weaknesses in reading. Structural equation modeling results suggest that the double-deficit hypothesis is an accurate model for understanding adult reading achievement. Better reading achievement was associated with better phonological awareness and faster rapid automatized naming in adults. Posthoc analyses indicated that individuals with double deficits had significantly lower reading achievement than individuals with single deficits or no deficits.     

Discriminal distance analysis supports the hypothesis that pigeons retrospectively encode event duration

A discriminal distance analysis procedure similar to that used by Roitblat (1980) was employed to test the hypotheses that animals either retrospectively (Spetch & Wilkie, 1983) or prospectively (Kraemer, Mazmanian, & Roberts, 1985) encode durations of events. Pigeons were required to discriminate 2-, 8-, and 10-sec presentations of light. Choices of red, orange, and green keys were correct after 2, 8, and 10 sec, respectively. The key elements in this design were (1) that some samples (8 and 10 sec) and some choice stimuli (red and orange) were more difficult to discriminate than were others, and (2) that an easy sample discrimination (2 vs. 8 sec) was mapped onto a difficult choice discrimination (red vs. orange), and vice versa. An examination of raw error scores and calculated confusion indexes in three experiments supported the hypothesis that subjects retrospectively, rather than prospectively, encode event duration.     

Testing the inference mediation hypothesis in a post-secondary context

The inference mediation hypothesis (IMH) assumes that individual difference factors that affect reading proficiency have direct and indirect effects on comprehension outcomes, with the indirect effects involving inference processes. The present study tested the IMH in a diverse sample of two and four-year college students in a task that emphasizes comprehension of the passage (traditional assessment) and a task that emphasizes complex problem solving (SBA). Participants were administered assessments of foundational skills that support reading, inference generation, a traditional assessment of comprehension proficiency, and a scenario-based reading assessment. The results support the IMH. However, the strength of the indirect relationships depended on the type of reading performance assessment. Coherence building inferences partially mediated the relationship for the traditional assessment. Elaborative inferences partially mediated the relationship for the scenario-based assessment. The results are discussed in terms of theories of purposeful reading and implications for understanding college readiness.     

Time-of-day discriminative learning in homing pigeons,Columba livia

Pigeons were trained on an operant procedure to discriminate between morning and afternoon when location did not vary (Experiment 1). The pigeons were placed on a fixed interval (FI) schedule in the morning and on a different FI schedule in the afternoon. Probe trials that occurred at the beginning of the training sessions were examined. The pigeons responded differently, depending on the time of day, reflecting the learning of a stable 24-h memory representation of the association between the FI schedules and the time of day. The pigeons from Experiment 1 were then clock shifted and tested twice, to determine whether they were relying on an endogenous circadian oscillator, an hourglass mechanism influenced by the photoperiod, or environmental noise to make the time-of-day discrimination (Experiment 2). The results of the second experiment indicated a circadian mechanism was most important for the observed time-of-day learning.     

Conditioned inhibition in feature negative discrimination learning with pigeons

Discrimination performance was investigated with pigeons using feature negative (FN) discrimination procedures which differed in the temporal arrangement of the stimuli on S? trials. In both procedures, a single common element was presented on reinforced (S+) trials. In thesimultaneous FN procedure, a distinguishing element was presented simultaneously with the common element of S? trials. In thesequential FN procedure, the distinguishing element preceded onset of the common element on S? trials. In two experiments, the sequential FN procedure yielded better discrimination performance. In Experiment 1, a summation test designed to separate learning and performance variables indicated that sequential FN subjects had learned the negative relationship between the distinguishing element and reinforcement while simultaneous FN subjects had not. In Experiment 2, summation and acquisition tests indicated that the distinguishing element developed inhibitory properties in the sequential FN procedure but not in the simultaneous FN procedure.     

Intradimensional vs. extradimensional transfer in the discriminative learning of goldfish and pigeons

Evidence of better intradimensional than extradimensional transfer was sought in naive goldfish trained under free-operant single-stimulus conditions (Experiment I), sophisticated pigeons trained under free-operant single-stimulus conditions (Experiment II), sophisticated pigeons trained under discrete-trials choice conditions (Experiment III), and naive pigeons trained under discrete-trials choice conditions (Experiment IV). The results provide no support for attention theory.     

Testing the spill-over hypothesis: meritocracy in enrolment in postgraduate education

This study contributes to the literature on educational transitions, specifically whether an equalising of opportunities at early educational transitions translates into more equal participation patterns at later stages (Spill-over versus maximally maintained inequality hypotheses). The case study approach used in this paper compares the enrolment profile of postgraduate students at a prestigious, research-led British university with the profile of the postgraduates’ undergraduate degree-awarding institution. The database for this research consists of government statistics and two purposefully administered surveys, one of undergraduate students (n = 709) and one of postgraduate students (n = 502). The study finds that the intake of new postgraduates is largely drawn from the most prestigious universities thus suggesting that graduates from lower tier institutions do not self-select themselves for further study at Oxford. The results lend support to the meritocracy hypothesis regarding the attainment levels of new postgraduate students and their propensity to gain government funding. There are, however, some discrepancies in transition patterns that advantage the already privileged. This lends support to the maximally maintained inequality hypothesis and suggests that there are social justice concerns in postgraduate education.

补缺假说与日语学习的若干思考

补缺假说认为目的语语境知识的缺失会导致母语语境知识发挥补缺作用,进而激活大脑中相应的母语表达式,这一观点为外语学习提供了新视角。对补缺假说的论证仅限于英语是不够的,是否适用于日语学习。中国的日语学习者在习得过程中,是否也会发生母语补缺以及对日语学习和教学的启示是怎样的。     

Testing the model-observer similarity hypothesis with text-based worked examples

Example-based learning is a very effective and efficient instructional strategy for novices. It can be implemented using text-based worked examples that provide a written demonstration of how to perform a task, or (video) modelling examples in which an instructor (the ‘model’) provides a demonstration. The model-observer similarity (MOS) hypothesis predicts that the effectiveness of modelling examples partly depends on the degree to which learners perceive the models to be similar to them. It is an open question, however, whether perceived similarity with the person who created the example, would also affect learning from text-based worked examples. Therefore, two experiments were conducted to investigate whether MOS would also play a role in learning from worked examples. In Experiment 1 (N = 147), students were led to believe via pictures and a short story that the worked examples were created by a male or female peer student. Males showed higher performance and confidence, but no effects of MOS on learning were found. In Experiment 2 (N = 130), students were led to believe that a peer student or a teacher created the examples. Again, no effects of MOS were found. These findings suggest that the perceived origin of text-based worked examples is not important for learning.     

Testing the instructional fit hypothesis: the case of self-explanation prompts

Cognitive science principles should have implications for the design of effective learning environments. The self-explanation principle was chosen for the current work because it has developed significantly over the last 20 years. Early formulations hypothesized that self-explanation facilitated inference generation to supply missing information about a concept or target skill, whereas later work hypothesized that self-explanation facilitated mental-model revision (Chi, Handbook of research on conceptual change, 2000). To better understand the complex relationship between prior knowledge, cognitive processing, and changes to a learner’s representation, two classes of self-explanation prompts (gap-filling and mental-model revision) were tested in the domain of physics problem solving. Prompts designed to focus the learner on gap-filling led to greater learning and a reduction in the amount of tutoring assistance required to solve physics problems. The results are interpreted as support for the instructional fit hypothesis—the idea that the efficacy of instruction is contingent on the match between the cognitive processing that the instruction elicits, how those processes modify the underlying knowledge representations for the task, and the utility of those representations for the task or problem.     

Evaluation of the double-deficit hypothesis in college students referred for learning difficulties

The present study explored the double-deficit hypothesis (DDH) in a sample of 146 college students with and without reading disabilities (RD). The results indicated that although both phonological awareness (PA) and visual naming speed (VNS) contributed to performance on measures of decoding and comprehension, their relative contribution was influenced both by the nature of the stimulus (word vs. nonword vs. text) and by the conditions of the task (timed vs. untimed). Similar results were obtained using an individual differences approach, or when between-group comparisons were made of individuals with deficits in PA or VNS. The relative representation of DDH subgroups in groups of adults with RD varied based on the classification criteria used to define RD. These results support the DDH, extend its applicability to adults, and have implications for diagnostic decision making.     

Within-event learning contributes to value transfer in simultaneous instrumental discriminations by pigeons

Following simultaneous discrimination training with pigeons, in which responding to the S−was reinforced on half of the trials and responding to the S− was never reinforced, we examined the effect on the S− of presenting the S− by itself and the effect on the S+ of presenting the S− by itself (relative to an S− or an S− for which there had been no single-stimulus presentations). For Group A−, responding to the S− presented by itself was always reinforced, whereas for Group A−, such responding was extinguished. For Group B−, responding to the S− presented by itself was always reinforced, whereas for Group B+, responding was extinguished. Although both Group A+ and Group A−tended to avoid their associated S− (relative to a control S−), Group A+ avoided its associated S− less than did Group A−. In contrast, although for Group B−, presentation of the S− alone increased the pigeons’ preference for its associated S−(relative to a control S+), for Group B−, presentation of the S−alone had little effect on its preference for its associated S+. These results suggest that presentation of one stimulus from a simultaneous discrimination has two independent and sometimes opposite effects on the other discriminative stimulus. First, it reduces the strength of within-event conditioning between the S+ and the S−, and second, if the value of the singly presented stimulus has increased, some of its newly acquired value will transfer retroactively to the stimulus with which it was originally paired.     

Testing a student generated hypothesis using student data

We describe an activity that allows students to experience the full process of a statistical investigation, from generating the research question, to collecting data and testing a hypothesis. Implementation of the activity is described both with and without use of clickers, handheld remotes that allow instant data collection.     

Reinstatement of postresponse stimuli prior to reward in delayed-reward discrimination learning by pigeons

Delayed-reward learning in pigeons was examined using a simultaneous red-green visual discrimination task in which the conditions during the delay interval were varied between groups. The nondifferential group received training in which the stimulus present during the 1-min delay was the same following a peck on the correct and incorrect colors. The other three groups received 1-min delay training in which different stimuli occurred in the delay interval following correct and incorrect choices. The differential group received continuous, differential stimuli during the delay. The reinstatement group received the differential stimuli in the 10 sec immediately following the choice and during the last 10 sec of the delay. The reversedcue group was treated in the same way, except that the 10-sec delay stimulus immediately following an incorrect response was also presented for 10 sec prior to reward on correct choices, and the stimulus following a correct response also occurred 10 sec before nonreward on incorrect choices. Nondifferential birds failed to learn the discrimination, while differential and reinstatement birds learned it readily. The reversed-cue birds learned to choose the incorrect stimulus. Differential and reinstatement birds showed no decrement in performance when the delay was increased to 2 min. These findings suggest that similarity of prereward and postresponse delay stimuli controls choice responding in long-delay learning, a finding compatible with both memorial and conditioned reinforcement interpretations.     

Simultaneous discrimination reversal learning in pigeons and humans: anticipatory and perseverative errors

Pigeons were trained on a two-choice simultaneous discrimination (red vs. green) that reversed midway through each session. After considerable training, they consistently made both anticipatory errors prior to the reversal and perseverative errors after the reversal, suggesting that time (or number of trials) into the session served as a cue for reversal. In Experiment 2, to discourage the use of time as a cue, we varied the location of the reversal point within the session such that it occurred semirandomly after Trial 10, 25, 40, 55, or 70. Pigeons still tended both to anticipate and to perseverate. In Experiment 3, we required 20 pecks to a stimulus on each trial to facilitate memory for the preceding response and sensitivity to local reinforcement contingencies, but the results were similar to those of Experiment 2. We then tested humans on a similar task with a constant (Experiment 4) or variable (Experiment 5) reversal location. When the reversal occurred consistently at the midpoint of the session, humans, like pigeons, showed a tendency to anticipate the reversal; however, they did not show perseverative errors. When the reversal location varied between sessions, unlike pigeons, humans adopted a win–stay/lose–shift strategy, making only a single error on the first trial of the reversal.